November 27, 2008

Glad to see that people are having downloading and success with the Celerra VM on VMware Workstation based on this original post. I wanted to provide a quick "HOWTO" to help customers Replicate between two VSAs, for many reasons - one of the most fun being VMware Site Recovery Manager.

Celerra Replicator (I hope the Celerra Product team doesn't read this) is a RIDICULOUSLY inexpensive (particularly when compared with the competition) but very sophisticated remote replication capability. It can support cool stuff like:

1:N and also N:1 replication fan-in/fan-out replication relationships (like with any technology there are operating envelopes and parameters)

It can support cascading topologies (i.e. site one replicates to site 2 with a given frequency, and then site 2 replicates the data from site 1 to site 3 at a different frequency

It has pretty sophisticated QoS mechanisms (i.e. you can setup different bandwidth use for different parts of the day

You can replicate all sorts of configs - CIFS/NFS/iSCSI, and fully supports thin provisioning at the source or the target

And of course - most interestingly of all - it's fully integrated with VMware Site Recovery Manager (so you can use this to build your own SRM playground.

Of course - SRM doesn't support NFS yet, so I focused this HOWTO on iSCSI - but it's very easy to see how you would do CIFS/NFS (just hit the other radio button in step 3)

Before you do this - make sure you have a working VSA - just follow the Celerra VSA HOWTO 101 here...

I've updated the OVF - tightened it up a bit. You can get the new one here

Ok - have you got it? Have you followed the 101? Want to add more storage - just follow the Celerra VSA HOWTO 201 here.

Ok... then read on...

Quickly then here - in this HOWTO:

Configuring NTP

Correcting the Replication Database (post Clone or deploy from OVF the Celerra VM's serial number is changed) - BIG thanks to Himabindu Tummala and Santosh PasulaReddy in Celerra Engineeringfor helping me figure this step out

Configuring an iSCSI LUN that will be used as a replication target

Configuring Celerra Replicator

One of our elite-delta squad VMware Specialists is putting the finishing touches on an "all in" doc and pair of Celerra VSAs to make setting up SRM with two Celerra VSAs a breeze, but you have every ingredient you need now with these HOWTOs (and SRM itself is a walk in the park).

One quick note - remember that if you are looking for support - post on http://forums.emc.com, in the Celerra, Celerra Simulator forum.

Next up to plate is the HOWTO on Avamar Virtual Edition, and I'm also going to do a HOWTO post on how to use the super-cool Replication Manager with the VSA. Rep Manager - aka "RM" can actually be used with all EMC's primary storage platforms, for all sorts of replication/test and dev use cases - for Exchange, SQL Server, Oracle, and also VMware VMs and VMFS datastores - NFS datastores being supported shortly.

Read on......

Step 1: Configuring NTP. This step ensures that the Celerra Control Stations and Datamovers that are participating in a replication session are timesync'ed against a network time protocol (NTP) server. This is required - if they are more than 10 minutes skewed, you cannot replicate (won't authenticate the connection between the source and the target) .

Step 2: Correcting the Replication Database. When the Celerra is deployed from a template, or cloned, or deployed by importing a Virtual Appliance OVF, the serial number changes. For those of you following from the 101 HOWTO, you saw how we needed to correct one of the Celerra Databases that stored the Ethernet interface MAC addresses (since clone/template deplpoy/OVF import change them). Likewise here, the Celerra replication database entry for the "loopback" (i.e. itself) is incorrect, and needs to be updated. This step in the process stops the replication services, blows away the database, and then re-initializes it.

Step 3: Configuring an iSCSI LUN that will be used as a replication target. Replication involves a source and a target - if you're replicating filesystems, then they are filesystems. If you are replicating LUNs (like we will here since I expect many of you will want to use this with Site Recovery Manager), then they are LUNs. This step shows how to configure an iSCSI LUN that will be the replication target. To be a replication target, it needs to have the same size as the source, it needs to be configured to be read only, and the filesystem has to be bigger than the LUN itself - ergo you need a bit of "space reservation". This "space reservation" is common to many storage use cases involving snapshots. The video suggest a minimum (and a maximum, most conservative) value. One nice thing is that EMC has always philosophically chosen that an "out of space condition" should cause snaps/replicas to fail, not production - so you really can't bork yourself.

Thanks. This cured the ills for my setup! I was able to modify both of the Celerra sims I have running with data on them. I had to delete the replication job that had already created, create a new job with the wizard, and it started going.

I got it done two nites ago and it has been running fine since (a good way to wrap up the holiday!) Without this mod, it would go for ~4-12 hrs before the job would stop.

Not sure if anyone has run into this.
I found out that the File System has to be the 20-150% bigger than the replicated LUN not just on the destination, but also on the Source. I found out the hard way and after playing around for a while (I was getting the "version set out of space" error when trying to replicate). Increasing the size of the dest. FS did not help. Finally I changed the sizes on both source/remote Celerras and worked like a charm.

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The opinions expressed here are my personal opinions. Content published here is not read or approved in advance by Dell Technologies and does not necessarily reflect the views and opinions of Dell Technologies or any part of Dell Technologies. This is my blog, it is not an Dell Technologies blog.